The present invention relates to residential and commercial heat release processes, which requires the burning of fuel with air. Specifically, the invention relates to processes regulated for achieving low nitrogen oxide (NOx), carbon monoxide (CO) and volatile organic chemicals (VOC) emissions.
This invention provides more economical means for achieving low emission levels, particularly oxides of nitrogen, while maintaining high efficiency. High efficiency also reduces greenhouse gases.
Residential units may include, among others, forced hot air heating and water heaters. Commercial units may include boilers and water heaters. Industrial units may include indirect heating such as radiant tubes.
The fuels combusted might be natural gas, refinery or process gas, and liquid distillate fuels like diesel fuel or #6 (residual) fuel oil.
NOx is an abbreviation for the collective species of nitrogen oxide and nitrogen dioxide, which are responsible for health problems, and the creation of smog. NOx is created in the intense heat of a combustion flame where nitrogen and oxygen are present. It has been long known that the suppression of flame temperature can reduce NOx significantly. NOx can also be created from fuel bound nitrogen and ammonia or other nitrogen bearing compounds that find its way into the fuel or combustion air. In this case, NOx is not reduced by a suppression of flame temperature, but NOx can be "chemically reduced" to N2 and carbon dioxide (CO.sub.2) in a hot fuel-rich flame that is carbon monoxide (CO) rich.
There are a number of methods for reducing NOx, as listed below. However, all come with some economic penalty or degradation in process performance. It is an object of this invention to provide a novel method and structure that will minimize the economic penalties associated with these NOx reducing methods.